Dual string automatic gas lift valve

ABSTRACT

An automatically operated, pressure responsive gas lift injection valve for use in a dual zone string utilizes a pressure operated switching valve for delivering injection gas to the tubing string having the highest column of fluid. The switching valve is responsive to the tubing pressure in each of the two production strings and, sensing the higher of the two tubing pressures, opens that string to lift gas injected through the casing annulus.

llnited States Patent [1 91 Douglas 1 Dec. 3, 1974 DUAL STRING AUTOMATICGAS LIFT VALVE Inventor: Bobby L. Douglas, Houston, Tex.

Dresser Industries, Inc., Dallas, Tex.

Mar. 1, 1974 Assignee:

Filed:

Appl. N0.:

US. Cl 417/112, 417/116, 417/117, 137/119 Int. Cl. F041 1/18, GOSd 11/00Field of Search 137/119; 417/116, 117, 417/112, 113

References Cited UNITED STATES PATENTS 1'1/1959 Bryan 417 112 3,348,50310/1967 Sidles 137/119 X Primary Examiner-C. J. l-lusar AssistantExaminerRichard E. Gluck Attorney, Agent, or FirmMichael J. Caddell [57]ABSTRACT An automatically operated, pressure responsive gas liftinjection valve for use in a dual zone string utilizes a pressureoperated switching valve for delivering injection gas to the tubingstring having the highest column of fluid. The switching valve isresponsive to the tubing pressure in each of the two production stringsand, sensing the higher of the two tubing pressures, opens that stringto lift gas injected through the casing annulus.

15 Claims, 3 Drawing Figures i l 36 5 23 i I 4 DUAL STRING AUTOMATIC GASLIFT VALVE BACKGROUND OF THE INVENTION In a dual zone completion wellwherein the formation pressure is insufficient to force formation fluidsto the top of the wellbore from either of the producing formations'andthe well is particularly suitable for gas lift operations, the method ofproducing such a well normally involves utilizing dual string productionequipment with gas lift valving apparatus in each production string.

When both injection valves are supplied with gas through the casingannulus, a problem arises in controlling the gas lift operation sinceboth valves may tend to open at the .same time. Since the fluid levelsin the two tubing strings are seldom at the same height, one string maybe receiving too much gas and the other may be receiving too little gas.Alternatively, when such simultaneous opening occurs itis possible thatneither string will receive sufficient gas to provide the gas liftingoperation desired. This results in highly inefficient production andgreatly increases the cost of the fluids recovered. This is due to thefact that a certain amount of gas is required to bring the well fluidsto the surface and when the strings are opened'to the annulus at thesame time, they tend to -rob each other and neither ends up withsufficient gas to lift the fluid column.

The present invention solves this problem by providing an alternatingintermittent gas lift valve that is responsive to fluidpressure in thetwo strings to allow injection gas to go only into the production stringhaving the highest column of fluid and therefore in greatest need forinjection gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I illustrates a dual productionstring in a well having multiple producing formations.

FIG. 2 illustrates a cross-sectional schematic view. of the apparatus ofthis invention.

FIG. 3 represents a top cross-sectional view looking down on theapparatus from section line 33 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. I a dualproductionstring is located in the borehole l1 and communicates with twoproducing formations. the upper formation 12 and a lower formation 13.The dual production tubing string 10 has a primary conduit 14communicating with the upper formation 12 via opening 15 in the bottomend of the tubing,

and a secondary string 16 communicating with the lower producingformation 13.

- A packer 17 is located in the annulus between the production string 10and the borehole 11 above the producing formation 12 to seal off theannulus above the packer from that below it. A second packer 18 islocated in the annulus below the upper formation to isolate theformations from each other.

The automatic, intermittent gas lift valve 20 is located in the dualproducing string 10 between the primary and secondary conduits 14 and16, above packer l7.

A closer view of the gas lift valve is shown in the cross-sectional viewof FIG. 2 in which the valve is shown as comprising two tubular adapterconduits 21 and 22 placed in parallel configuration and arranged toalign coaxially with the dual production strings l4 and 16 respectively.The tubular adapters 21 and 22 may be threadedly joined to theproduction conduit or may be joined by use of connector collars 23 asshown in the figure.

The gas lift valve apparatus utilizes a substantially solid body portion24 in which has been formed dual primary valving chambers 25a and 25b,dual backflow checkvalve chambers 26a and 26b, gas lift flow passages 27and 28a and 28b, and gas injection ports 29a and 29b.

Gas lift passage 27 is substantially centrally located in the upperportion of body portion 24 and passes downward generally parallel withconduits 21 and 22 whereupon it intersects dual gas flow passages 28aand 28b which branch generally outward and then turn downward. Passages28a and 28b pass downward generally parallel to conduits 21 and 22 andflow into backflow checkvalve chambers 26a and 26b.

Spring loaded checkvalves 30 and 31 are located movably up and down inchambers 26a and 26b respectively and are continuously urged upward intosealing engagement with the bore openings of passages 28a and 28b bycoil springs 32 and 33 respectively.

The lower portion of chambers 26a and 26b communicate with the primaryvalving chambers 25a and 25b via central openings 34b and 34a locatedtherebetween. Primary chambers 25a and 25b are separated by an inwardlyprojecting wall 35 having an opening located substantially in the centerthereof. A sliding valve member 37 is located slidably in the opening inwall 35 and a sleeve seal 36 is located in the wall opening abuttingvalve member 37 in sealing engagement to prevent fluid or gascommunication between the primary valving chambers.

The opening in wall 35 is arranged so that it is substantially alignedwith opp'osingports 29a and 29b in body 24 so that valve member 37 canmove laterally from closing one port to closing the opposite port. Asillustrated in the figure, valve member 37 is in the position of openingport 29a and closing port 29b.

Ports 29a and 2% correspond with matching ports through the wall ofconduits 21 and 22, respectively, thereby forming channels ofcommunication from the inner bores of the conduits to the primary valvechambers.

Injection gas is supplied to the main flow passage 27 via a standard gasinjection valve .38 having a tubular threaded connection adapter 39which engages the upper portion of body 24 and communicates with pasofbody 40. Body 40 also forms a gas chamber 46 which contains an inertcompressed gas which gas also fills the inner portion of bellows 41. Aninterconnecting cap 47 is sealingly attached to the top of body member40 enclosing gas chamber 46 and is securedly attached by means such aswelding at each end to conduits 21 and 22. Likewise, body 24 issimilarly attached to conduits 21 and 22 at each side.

FIG. 3 illustrates a top view of the gas lift valve assembly as it islocated substantially centralized in the wellbore casing 48. Gas passagedown the annulus 49 easily flows around the apparatus and has access toports 45 in the upper lift valve 38.

In typical operation, referring to FIGS. 1 and 2, pressurized injectiongas is pumped into the well annulus through means such as piping 50. Thegas enters the upper gas valve 38 through ports 45, thereby compressingbellows 41, moving valve element 43 upward out of bore 39a and allowinggas to flow down passages 27, 28a and 28b.

Meanwhile, prior to the opening of element 43, formation fluid hasaccumulated in the conduits 21 and 22 and the fluid in the conduithaving the highest level (conduit 21 in the case illustrated) appliesthe greatest hydrostatic pressure force on the slidable valve member 37through ports 29a or 29b thereby moving the member into blockingposition over the opposite port. This allows the pressurized injectedgas to move the spring loaded checkvalve 30 or 31 downward and moves thegas past the valve 37 and through whichever port is opened. The nextpulse of pressurized gas may move out through the opposite portdepending upon the rate of build-up of the two different fluid levels inthe conduits and also depending upon the time required for the injectiongas in the annulus to build-up sufficient pressure again to open theupper gas injection valve 38.

As an alternative, a pressure cycling device containing a timer may beused at the surface to apply intermittent pressure applications to theannulus gas should the rate of fluid build-up in the conduits be tooslow to efficiently utilize a constant annulus gas pressure.

A distinct advantage of this apparatus is that it automatically injectsgas into the column of fluid having the greatest need for the gas, i.e.the highest column, regardless of which column received the precedinggas charge. This provides the highest possible gas lifting efficiency,particularly when one of the formations is considerably higher flowingformation than the other.

Although a specific preferred embodiment of the present invention hasbeen described in the detailed description above, the description is notintended to limit the invention to the particular forms or embodimentsdisclosed therein, since they are to be recognized as illustrativerather than restrictive and it will be obvious to these skilled in theart that the invention is not so limited. For example, the valvingmember is illustrated as elongated and may be cylindrical, polygonal orother configuration in cross-sectional shape. Also other typecheckvalves than those shown could be utilized. The invention isdeclared to cover all changes and modiflca tions of the specific exampleof the invention herein disclosed for purposes of illustration which donot constitute departures from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A dual string, gas lift injection valve assembly comprising:

body means adapted to engage two strings of conduit;

passage means in said body arranged to communicate with the strings ofconduit;

checkvalve means in said passage means adapted to allow fluid flowthrough said passage means in one direction only;

pressure responsive valve means in said passage means communicating withthe conduit strings, said pressure responsive means arranged in saidpassage means to receive fluid pressure from the conduit strings and tomove responsively thereto to open and close said passage meansalternatively to each of the conduit strings; and

means on said body means for delivering pressurized gas to said passagemeans.

2. The gas lift injection valve assembly of claim 1 wherein said bodymeans further comprises dual lowcr chambers separated by a centrallylocated wall portion and dual upper chambers communicating with saidlower chambers and with said passage means.

3. The gas lift injection valve assembly of claim 2 wherein said passagemeans further comprises a generally centrally located upper passageextending from said pressurized gas delivery means into said body means;two branch passages extending from said upper passage each to one ofsaid dual upper chambers; secondary passages extending from said dualupper chambers to said dual lower chambers; and, port means between saidlower chambers and the conduit strings.

4. The gas lift injection valve assembly of claim 1 wherein saidpressure responsive valve means further comprises a dual-element valvemember sealingly and slidably mounted in said body means and havingpressure responsive areas thereon; and, dual valve seats in said passagemeans arranged to receive in sealing engagement said valve member, eachsaid valve seat circumscribing said passage means between said bodymeans and the conduit strings.

5. The gas lift injection valve assembly of claim 1 wherein said meansfor delivering pressurized gas comprises a bellows-type, differentialpressure operated valve assembly having ports therein communicating withthe annulus of the wellbore and further having a valved flow passagebetween said ports and said passage means.

6. The gas lift injection valve assembly of claim 1 further comprisingtwo tubular elongated conduit adapters attached one to each side of saidvalve assembly and arranged to align co-axially with the dual stringproduction tubing in a dual-zone well; each of said conduit adaptershaving connection means at each end for connection to standard sectionsof oil well production tubing.

7. A dual string gas lift valve assembly for use in a wellbore, saidassembly comprising:

a body member adapted to be engaged with a dual conduit string;

gas passage means through said body member communicating from theannulus of the wellbore to the dual conduit string; and

valve means in said body member for alternately opening said passagemeans to one conduit string while simultaneously closing said passagemeans to the other conduit string;

said valve means having pressure responsive areas thereon exposed topressures in each of the conduit strings; said valve means beingslidably and sealingly mounted in said body member and arranged to bemoved slidably therein by pressures in the conduit strings.

8. The gas lift valve assembly of claim 7 further comprising checkvalvemeans in said passage means arranged to allow flow into the conduitstrings, but prevent flow from the conduit strings.

9. The gas valve assembly of claim 8 further comprising elongatedtubular conduit adapters attached to said valve assembly and arranged tobe coaxially aligned with the conduit strings and further havingconnection means at each end for connection to standard tubing sections.

10. The gas lift valve assembly of claim 9 further comprising pressureresponsive injection gas regulating means connected to said gas liftvalve assembly and having fluid communication passages from the annulusof the well to said valve assembly, with pressure responsive valve meansin said fluid communication passages in valving relationship therewith.

11. The gas lift valve assembly of claim 10 wherein said body memberfurther comprises a generally solid body having dual upper chamberscontaining said checkvalve means and dual lower chambers divided by agenerally centrally located wall section; with said valve means in saidbody member comprising an elongated valve body slidably and sealinglymounted in said wall section; with said gas passage means communicatingfrom said regulating means through said dual upper chambers and saiddual lower chambers to dual ports in the wall of said body at said lowerchambers, with one said port in each lower chamber, said each port beingcoaxially aligned with said elongated valve body and arranged to bealternatively closed and opened by said valve body.

12. A dual string gas injection assembly for use in gas-lift oil wellshaving dual production strings, said assembly comprising:

a body member adapted to be connected between two well conduits andinserted in the wellbore; dual gas flow channels in said body memberarranged to communicate one with each of the well conduits;

a pressure responsive valve member movable in both of said gas flowchannels and arranged to open and close said channels alternatively,said valve member being movable in response to fluid pressure from thewell conduits; and

pressurized gas supply means communicating with said flow channels andarranged to provide pressurized gas to said flow channels.

13. A pressurized gas injection assembly for use in gas-lift operationin a dual string well; said assembly comprising: a

a generally solid body member adapted to be placed between two wellconduits and having port means therein communicating with the wellconduits;

dual flow channels in said body member communicating with said portmeans, each of said channels having an upper chamber and a lowerchamber. with said two lower chambersbeing laterally adjacent andseparated by a wall section;

checkvalve means in each of said upper chambers arranged to allow flowthrough said channels to said port means, but prevent flow from saidport means through said flow channels;

a slidable valve member sealably located in said wall section andarranged to alternately open one of said flow channels to said portmeans while simultaneously closing said other flow channel to said portmeans;

pressure responsive areas on said valve member arranged to receive fluidpressure from the well conduits;

means for connecting said body member to the well conduits; and,

a gas injection valve communicating between the well annulus and saidflow channels and adapted to respond to pressurized gas in the annulusto open said injection valve to allow gas from the annulus to flowtherethrough.

14. The gas injection assembly of claim 13 wherein said connecting meansfurther comprises elongated tubular sections securedly attached to saidbody member and coaxially aligned with the production strings in thewellbore; said tubular sections having connection means at each end forconnection with standard tubing sections.

15. The gas injection assembly of claim 14 wherein said gas injectionvalve comprises a tubular cylindrical housing having a central borepassage, port means through the wall thereof, an expandable bellowselement securedly attached therein to define an expansion-contractionchamber, and a valve member on said bellows element arranged to open andclose said cen-

1. A dual string, gas lift injection valve assembly comprising: bodymeans adapted to engage two strings of conduit; passage means in saidbody arranged to communicate with the strings of conduit; checkvalvemeans in said passage means adapted to allow fluid flow through saidpassage means in one direction only; pressure responsive valve means insaid passage means communicating with the conduit strings, said pressureresponsive means arranged in said passage means to receive fluidpressure from the conduit strings and to move responsively thereto toopen and close said passage means alternatively to each of the conduitstrings; and means on said body means for delivering pressurized gas tosaid passage means.
 2. The gas lift injection valve assembly of claim 1wherein said body means further comprises dual lower chambers separatedby a centrally located wall portion and dual upper chamberscommunicating with said lower chambers and with said passage means. 3.The gas lift injection valve assembly of claim 2 wherein said passagemeans further comprises a generally centrally located upper passageextending from said pressurized gas delivery means into said body means;two branch passages extending from said upper passage each to one ofsaid dual upper chambers; secondary passages extending from said dualupper chambers to said dual lower chambers; and, port means between saidlower chambers and the conduiT strings.
 4. The gas lift injection valveassembly of claim 1 wherein said pressure responsive valve means furthercomprises a dual-element valve member sealingly and slidably mounted insaid body means and having pressure responsive areas thereon; and, dualvalve seats in said passage means arranged to receive in sealingengagement said valve member, each said valve seat circumscribing saidpassage means between said body means and the conduit strings.
 5. Thegas lift injection valve assembly of claim 1 wherein said means fordelivering pressurized gas comprises a bellows-type, differentialpressure operated valve assembly having ports therein communicating withthe annulus of the wellbore and further having a valved flow passagebetween said ports and said passage means.
 6. The gas lift injectionvalve assembly of claim 1 further comprising two tubular elongatedconduit adapters attached one to each side of said valve assembly andarranged to align co-axially with the dual string production tubing in adual-zone well; each of said conduit adapters having connection means ateach end for connection to standard sections of oil well productiontubing.
 7. A dual string gas lift valve assembly for use in a wellbore,said assembly comprising: a body member adapted to be engaged with adual conduit string; gas passage means through said body membercommunicating from the annulus of the wellbore to the dual conduitstring; and valve means in said body member for alternately opening saidpassage means to one conduit string while simultaneously closing saidpassage means to the other conduit string; said valve means havingpressure responsive areas thereon exposed to pressures in each of theconduit strings; said valve means being slidably and sealingly mountedin said body member and arranged to be moved slidably therein bypressures in the conduit strings.
 8. The gas lift valve assembly ofclaim 7 further comprising checkvalve means in said passage meansarranged to allow flow into the conduit strings, but prevent flow fromthe conduit strings.
 9. The gas valve assembly of claim 8 furthercomprising elongated tubular conduit adapters attached to said valveassembly and arranged to be coaxially aligned with the conduit stringsand further having connection means at each end for connection tostandard tubing sections.
 10. The gas lift valve assembly of claim 9further comprising pressure responsive injection gas regulating meansconnected to said gas lift valve assembly and having fluid communicationpassages from the annulus of the well to said valve assembly, withpressure responsive valve means in said fluid communication passages invalving relationship therewith.
 11. The gas lift valve assembly of claim10 wherein said body member further comprises a generally solid bodyhaving dual upper chambers containing said checkvalve means and duallower chambers divided by a generally centrally located wall section;with said valve means in said body member comprising an elongated valvebody slidably and sealingly mounted in said wall section; with said gaspassage means communicating from said regulating means through said dualupper chambers and said dual lower chambers to dual ports in the wall ofsaid body at said lower chambers, with one said port in each lowerchamber, said each port being coaxially aligned with said elongatedvalve body and arranged to be alternatively closed and opened by saidvalve body.
 12. A dual string gas injection assembly for use in gas-liftoil wells having dual production strings, said assembly comprising: abody member adapted to be connected between two well conduits andinserted in the wellbore; dual gas flow channels in said body memberarranged to communicate one with each of the well conduits; a pressureresponsive valve member movable in both of said gas flow channels andarranged to open and close said channels alternatively, said valvemember being movable in response to fluid pressurE from the wellconduits; and pressurized gas supply means communicating with said flowchannels and arranged to provide pressurized gas to said flow channels.13. A pressurized gas injection assembly for use in gas-lift operationin a dual string well; said assembly comprising: a generally solid bodymember adapted to be placed between two well conduits and having portmeans therein communicating with the well conduits; dual flow channelsin said body member communicating with said port means, each of saidchannels having an upper chamber and a lower chamber, with said twolower chambers being laterally adjacent and separated by a wall section;checkvalve means in each of said upper chambers arranged to allow flowthrough said channels to said port means, but prevent flow from saidport means through said flow channels; a slidable valve member sealablylocated in said wall section and arranged to alternately open one ofsaid flow channels to said port means while simultaneously closing saidother flow channel to said port means; pressure responsive areas on saidvalve member arranged to receive fluid pressure from the well conduits;means for connecting said body member to the well conduits; and, a gasinjection valve communicating between the well annulus and said flowchannels and adapted to respond to pressurized gas in the annulus toopen said injection valve to allow gas from the annulus to flowtherethrough.
 14. The gas injection assembly of claim 13 wherein saidconnecting means further comprises elongated tubular sections securedlyattached to said body member and coaxially aligned with the productionstrings in the wellbore; said tubular sections having connection meansat each end for connection with standard tubing sections.
 15. The gasinjection assembly of claim 14 wherein said gas injection valvecomprises a tubular cylindrical housing having a central bore passage,port means through the wall thereof, an expandable bellows elementsecuredly attached therein to define an expansion-contraction chamber,and a valve member on said bellows element arranged to open and closesaid central bore passage.